A great American story and a dazzling evisceration of one of the country’s foundational myths, Jane Campion’s “The Power of the Dog” centers on Phil Burbank (Benedict Cumberbatch), a swaggering man’s man.

Campion’s touch is more subtle in “The Power of the Dog” although her knife work is similarly swift, sure, inexorable and unforgiving.

The story takes place in 1925, more than three decades after the Census Bureau declared the frontier closed and the same year that Buster Keaton starred in the comedy “Go West.” Time seems to have come to a standstill for Phil, though the Burbank family owns one of the area’s few cars.

The story turns on what happens when George marries Rose (Kirsten Dunst), a widow with a teenage son, Peter (Kodi Smit-McPhee, who evokes the young Anthony Perkins of “Psycho”).

Phil sees Rose as an opportunist and writes a letter of complaint to his parents, whom the brothers, more comically than fondly, refer to as the Old Lady and Old Gent (Frances Conroy and Peter Carroll).

When Rose first enters the Burbank house, Campion meaningfully pictures her in its gloom, the character’s pale face flickering like a weak light.

“The Power of the Dog” is a story of the Intermountain West, a sun-blasted realm of cowboys and wide-open spaces, desolation and self-reliance.

With the arrival of Rose and Peter, the story also becomes something of a female Gothic, one of those eerie stories about women in suffocating domestic spaces haunted by ghosts (literal and otherwise) and a-swirl with repressed desire.

Campion, who wrote the screenplay for “The Power of the Dog,” has pared the story down to its essentials, initially building on a series of oppositions, some starkly visible, others more covert.

For his part, George tends toward quiet, using as few words as possible, including when he’s being goaded by Phil, who derisively calls him Fatso.

As has often been the case, including in old Hollywood, these divisions are more complex than they seem and so are Phil and George, whose lifelong dynamic is disrupted by Rose and Peter, a spidery, bookish boy underestimated by everyone.

“The Power of the Dog”: Benedict Cumberbatch is earning high praise for his performance in Jane Campion’s new psychodrama.

Because while Rose hardens Phil’s shell, Peter chips away at it, providing glimpses of the other part of Phil that this man jealously guards, heartbreakingly alone with memories of a dead cowboy he still loves.